It is known that thin bimorph microcantilevers can undergo bending (deflection) due to differential stresses following exposure to and binding of a compound from their environment, for example in a fluid sample. Soft microcantilevers having spring constants less than 0.1 N/m are sensitive to stress differentials that arise as a result of interactions between extremely small amounts of a substrate material on a surface of the microcantilever and one or more materials in a sample. For a given microcantilever with a specially designed coating layer, the deflection yields information about components of the environment to which the microcantilever is exposed.
Microcantilevers are capable of detecting calorimetric enzyme-mediated catalytic biological reactions with femtoJoule resolution. (Thundat et al., “Microcantilever Sensors”, Microscale Thermophysical Engr. 1, pgs. 185-199, 1997.) Further, oligonucleotide interactions within a sample can be detected using a monolithic array of test sites formed on a surface to which the sample is applied as shown in U.S. Pat. No. 5,653,939.
It is also known to provide integrated chips to categorize molecules in a biochemical sample. For example, U.S. Pat. No. 6,123,819 to Peeters discloses a design for an integrated chip having an array of electrodes at the atomic or nano scale. The chip can be used to characterize single molecules in a solution such as individual proteins, complex protein mixtures, DNA, or other molecules.
In recent years, microfludics technology employing microcantilevers has emerged to provide a “lab-on-a-chip” for chemical analysis of biomaterials. For example, U.S. Pat. No. 6,054,277 to Furcht et al. discloses a genetic testing system that includes an integrated, unitary microchip-based detection device with microfluidic controls. The device employs a microcantilever sensor to detect a biochemical reaction in a single detection chamber having capillary interconnects. However, to analyze a number of solutions simultaneously, it would be necessary to utilize an equal number of these chips